Oil warming system and method for an electric motor

ABSTRACT

Various disclosed embodiments include oil warming systems, electric motors, and vehicles. In an illustrative embodiment a system includes an oil reservoir, a motor stator, and an oil pump. The oil reservoir is configured to hold oil therein. The motor stator is positioned such that at least a portion thereof is positioned within the oil reservoir where the at least the portion of the motor stator is in thermal communication with the oil while the oil reservoir includes the oil therein. The motor stator is configured to warm the oil while in an oil warming mode. The oil pump is fluidly coupled to the oil reservoir and is configured to draw oil out of the oil reservoir.

INTRODUCTION

The present disclosure relates to warming oil for an electric motor. Thestatements in this section merely provide background information relatedto the present disclosure and may not constitute prior art.

In an electric motor environment, an electric oil pump typically is usedto provide oil flow rate to meet the demand of cooling and lubrication,however at startup in low temperatures high oil viscosity not onlyrequires more power consumption from the electric pump to overcomesystem impedance but also can limit the amount of flow and pressurecapacity due to the finite power, flow, pressure, and capability of theelectric pump. Current approaches use high pump power along with filtergrading to overcome system impedance at low oil temperatures to overcomethe pressure drop.

The present background is provided by way of illustrative environmentalcontext only. It will be readily apparent to those of ordinary skill inthe art that the principles of the present disclosure may be implementedin other environmental contexts equally.

BRIEF SUMMARY

Various disclosed embodiments include oil warming systems, electricmotors, and vehicles.

In an illustrative embodiment an electrical motor system includes an oilreservoir, a motor stator, and an oil pump. The oil reservoir isconfigured to hold oil therein. The motor stator is positioned such thatat least a portion thereof is positioned within the oil reservoir whereat least a portion of the motor stator is in thermal communication withthe oil while the oil reservoir includes the oil therein. The motorstator is configured to warm the oil while in an oil warming mode. Theoil pump is fluidly coupled to the oil reservoir and is configured todraw oil out of the oil reservoir.

In another illustrative embodiment an electric motor includes a motorstator and a motor rotor configured to rotate relative to the motorstator. An oil reservoir is configured to hold oil therein such that aportion of the motor stator is in thermal communication with the oilwhile the oil reservoir include the oil therein. The motor stator iselectrically couplable to receive electrical power in an oil warmingmode. The motor stator is configured to increase a temperature of theoil while in the oil warming mode. An oil pump is fluidly coupled to theoil reservoir and configured to draw oil out of the oil reservoir. Atleast one oil sprayer may be coupled to the oil pump and configured tospray at least one end of the motor rotor.

In another illustrative embodiment a vehicle includes a vehicle body, anelectrical motor system, and at least one wheel. The electrical motorsystem includes an oil reservoir, a motor stator, and an oil pump. Theoil reservoir is configured to hold oil therein. The motor stator ispositioned such that at least a portion thereof is positioned within theoil reservoir where the at least the portion of the motor stator is inthermal communication with the oil while the oil reservoir includes theoil therein. The motor stator is configured to warm the oil while in anoil warming mode. The oil pump is fluidly coupled to the oil reservoirand is configured to draw oil out of the oil reservoir. The at least onewheel is coupled to the vehicle body and configured to be driven by atleast one motor having a motor stator and a motor rotor coupled to adrivetrain for the at least one wheel, the motor rotor being configuredto rotate relative to the motor stator.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is illustrated and described herein withreference to the various drawings, in which like reference numbers areused to denote like system components/method steps, as appropriate, andin which:

FIG. 1 is an exploded view in partial schematic form of an illustrativeoil circulation system for an electric motor;

FIG. 2 is a perspective view of an electric motor system including theoil circulation system in a stator warming configuration and oil lubepath through oil spray bar of FIG. 1 ;

FIG. 3 is a perspective view in partial cut-away view of the electricmotor system and the motor stator in the oil warming configurationinterfacing with oil in a sump of FIG. 2 ;

FIG. 4 is a schematic diagram of an illustrative vehicle including theelectric motor system of FIG. 2 ;

FIG. 5 is a flow chart of an illustrative method of warming oil for anoil spraying system for an electric motor system;

FIG. 6 is a schematic diagram of an illustrative heat exchanger of theelectrical motor system with a bypass valve for the heat exchanger in anopen state;

FIG. 7 is a schematic diagram of an illustrative heat exchanger of theelectrical motor system with a bypass valve for the heat exchanger in aclosed state;

FIG. 8 is a flow chart of an illustrative method of bypassing a heatexchanger in an electric motor system;

FIG. 9 is a block diagram of an illustrative vehicle; and

FIG. 10 is a block diagram illustrating an embodiment of the controllerof the electric motor assembly 100 of FIG. 9 .

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented here.

Various disclosed embodiments include illustrative oil warming systems,electric motors, and vehicles.

By way of overview, in various embodiments a system includes an oilreservoir adapted to submerge a portion of a motor stator in oil storedtherein. The oil in the oil reservoir is placeable in thermalcommunication with the motor stator and the motor stator is configuredto warm the oil in an oil warming mode. In various embodiments, in theoil warming mode, the motor stator receives power from a motor drive,such as an inverter, that, while causing heat generation in the windingsof the motor stator, does not induce torque generation in the motorrotor, such as power at a fixed magnitude along the d-axis. In otherembodiments, a current is induced (fixed magnitude or otherwise) whileholding the motor rotor stationary, such as by using a mechanical brakeor a vehicle braking system. An oil pump is coupled to the oil reservoirand configured to draw oil out of the oil reservoir. At least one oilsprayer may be coupled to the oil pump and configured to spray at leastone end of the motor rotor.

Still by way of overview, various embodiments use an electric motor,such as without limitation an electric motor of an electric vehicle, asan active heat source to heat up the oil by using a portion of thestator winding that is submerged under oil. For example, in variousembodiments oil may be sprayed directly onto exposed end-windings. Itwill be appreciated that heating up the oil may help contribute toincreasing oil flow capacity and reducing electric pump powerconsumption. Thus, in various embodiments using the heated motor statorcan help contribute to reducing load on the pump. Various embodimentscan also help contribute to providing a high flow rate of low viscosityoil to circulate during cold starts and low temperature vehicleoperation, thereby helping protect gears and bearings and helpingcontribute to improving durability and life of a drive unit of anelectric vehicle.

Referring now to FIGS. 1-3 , in various embodiments an illustrativesystem 120 is provided for warming and distributing oil in an electricalmotor system 100. In various disclosed embodiments, a non-limitingexample given by way of illustration only of the electrical motor system100 is that of an electric motor for an electric vehicle. It will beappreciated that the example of the electrical motor system 100 as anelectric motor for an electric vehicle is given by way of illustrationonly and not of limitation. It will also be appreciated that no suchlimitation of the electrical motor system 100 as an electric motor foran electric vehicle is intended and is not to be inferred. To that end,the electric motor system 100 may be any type of electric motor asdesired for a particular application.

Accordingly, it will be appreciated that the electrical motor system 100may be any type of electrical motor as desired for a particularapplication. For example, in some embodiments the electrical motorsystem 100 may be an alternating current (AC) motor and in some otherembodiments the electrical motor system 100 may be a direct current (DC)electrical motor. In embodiments in which the motor 100 is an AC motor,the electrical motor system 100 may be any type of AC motor as desiredfor a particular application, such as without limitation inductionmotors (also known as asynchronous motors) either single phase orpolyphase and synchronous motors either reluctance or hysteresis. Inembodiments in which the electrical motor system 100 is a DC motor, theelectrical motor system 100 may be any type of DC motor as desired for aparticular application, such as without limitation permanent magnet DCmotors, series DC motors, shunt DC motors, and compound DC motors. Inthe interest of brevity, non-limiting, illustrative examples of an ACmotor for the electrical motor system 100 are provided herein forpurposes of illustration only and not of limitation. However, it isagain emphasized that the electrical motor system 100 is not limited toan AC motor (of any type) and, in some embodiments, may be a DC motor.

In various embodiments the electrical motor system 100 includes the oilwarming system 120 and a motor 114, the motor including a motor stator109 and a motor rotor 115. The oil warming system 120 (also referred toas an oil delivery system in some embodiments) includes an oil reservoir108. Various embodiments of the oil reservoir 108 are contemplated,including an oil reservoir 108 that includes a separate oil sump, an oilreservoir 108 that is formed in another structure of the vehicle or theelectrical motor system 100, such as an engine casing, a casing of theelectrical motor system 100, and the like.

In various embodiments, the oil reservoir 108 is configured to receiveat least a portion of the motor stator 109 therein such that the motorstator 109, such as the portion received in the oil reservoir 108, is inthermal communication with oil held in the oil reservoir (while the oilis therein). In some of these embodiments, the oil reservoir 108 isconfigured to submerge a portion of a motor stator 109 in the oil.

An oil circuit is adapted to provide the oil from the oil reservoir 108to various systems for lubrication and cooling thereof. The oil in theoil reservoir 108 may be in thermal communication with the motor stator109. The motor stator 109 may be configured to warm the oil in an oilwarming mode, for example, when temperatures are low and oil viscosityis high, by providing electrical power to the stator 109. By providingelectrical power to the stator 109, current resistance within the statorcauses a rise in temperature in the stator 109. Because stator 109 is inthermal contact with the oil in oil reservoir 108, it is heated and theviscosity is decreased.

In various embodiments, the oil circuit includes the oil reservoir 108,an inlet in the oil reservoir 108, such as a suction filter 101, an oilpump 102, an oil filter 103, a heat exchanger 104, oil spray bars 105,and an oil tube 107. In various embodiments, the oil pump 102 is fluidlycoupled to the oil reservoir 108 and adapted to draw oil out of the oilreservoir 108 through the suction filter 101. The oil pump 102 may beany type of suitable oil pump as desired for a particular application.Oil pumps are well known to those of skill in the art and, as a result,explanation of construction and operation is not necessary for anunderstanding of disclosed embodiments by one of skill in the art. Afterbeing drawn from the oil reservoir 108 through the suction filter 101 bythe oil pump 102, the oil is pumped through the filter 103 and throughthe heat exchanger 104 (or through a heat exchanger bypass) before beingdelivered to the motor stator 109. In various embodiments, at least oneoil sprayer 105 is fluidly coupled to the oil pump 102 downstream of theoil filter 103 and the heat exchanger 104 and is configured to spray atleast one component of the motor stator 109, such as an end winding 113of the motor stator 109. In various embodiments, the oil tube is alsodownstream of the oil filter 103 and the heat exchanger 104 and isconfigured to deliver oil to an interior of the motor stator 109. In theembodiment illustrated in FIGS. 1-3 , the oil tube 107 is downstream ofthe at least one oil sprayer 105 and receives the oil via a cover tube106 positioned within a cover of the electrical motor system 120.

In various embodiments, the oil reservoir 108 includes an oil sump 110.In various embodiments, the oil filter 103 is coupled between the oilpump 102 and the oil sprayer(s) 105 and is configured to filter oilmoving from the oil pump 102 and to the oil sprayer(s) 105. The oilfilter 103 may be any type of suitable oil filter as desired for aparticular application. Oil filters are well known to those of skill inthe art and, as a result, explanation of construction and operation isnot necessary for an understanding of disclosed embodiments by one ofskill in the art.

In various embodiments, the oil sprayer(s) 105 include at least twosprayer bars 111 having multiple outlet holes 112. It will beappreciated that any number of the oil sprayers 105 may be used asdesired for a particular application. In some embodiments, more than oneof the oil sprayers 105 may be used. In some other embodiments, only oneoil sprayer 105 is used. It will also be appreciated that any number ofthe sprayer bars 111 may be used as desired for a particularapplication. In some embodiments, if desired at least two of the sprayerbars 111 are used. In some other embodiments, only one sprayer bar 111is used.

In various embodiments, the heat exchanger 104 is fluidly coupledbetween the oil pump 102 and the oil sprayer(s) 105. As will bediscussed in greater detail below, in various embodiments, a bypassvalve 130 (FIGS. 6 and 7 ) is coupled in parallel with the heatexchanger 104 and is adapted to permit oil to bypass the heat exchanger104. In various embodiments, the heat exchanger 104 is adapted toreceive heated oil from the oil pump 102 and reject heat from the oilbefore supplying the oil back to the oil sprayer(s) 105. The heatexchanger 104 may be any type of heat exchanger as desired for aparticular application, such as without limitation a tube-and-shell heatexchanger, a cross-flow heat exchanger, a counter-flow heat exchanger, aplate heat exchanger, and the like. Heat exchangers are well known tothose of skill in the art and, as a result, explanation of constructionand operation is not necessary for an understanding of disclosedembodiments by one of skill in the art.

The oil sprayer(s) 105 is adapted to spray oil onto exposed end windings113 of the motor stator 109. In some embodiments the oil sprayer(s) 105adapted to spray oil onto exposed ends of the motor rotor 115 and theexposed end windings 113 of the motor stator 109.

In various embodiments, the oil tube 107 is adapted to provide oil tothe motor rotor 115 for the cooling and lubrication thereof. In some ofthese embodiments, a cover tube 106 is adapted to supply the oil to theoil tube 107. After the oil is supplied to the motor stator 109 and themotor rotor 115 and used for lubrication and/or cooling, the oil isreturned to the oil reservoir 108.

In various embodiments, the oil reservoir 108 is adapted to submerge aportion of the motor stator 109 in oil stored therein. The motor stator109 may be electrically couplable to receive electrical power in an oilwarming mode. The oil pump 102 may be coupled to the oil reservoir 108and may be configured to draw oil out of the oil reservoir 108. The oilsprayer(s) 105 may be coupled to the oil pump 102 and configured tospray at least one end of the motor stator 109.

The electric motor 100 also includes the motor rotor 115. The motorrotor 115 is adapted to rotate relative to the motor stator 109.Referring now to FIG. 4 , in various embodiments a vehicle 300 includesa vehicle body 310 and at least one wheel 335 coupled to the vehiclebody 310 that is adapted to be driven by at least one motor 100 of thepresent disclosure, including the motor stator 109 and the motor rotor115 that is coupled to a drivetrain for the at least one wheel 335. Forexample, as depicted in FIGS. 1-3 , the motor rotor 115 is configured torotate relative to the motor stator 109, the oil reservoir 108 isadapted to submerge a portion of the motor stator 109 in oil, and themotor stator 109 is electrically couplable to receive power from a motordrive, such as AC power from an inverter, in an oil warming mode. Theoil pump 102 is fluidly coupled to the oil reservoir 108 and is adaptedto draw oil out of the oil reservoir 108. The oil sprayer(s) 105 isfluidly coupled to the oil pump 102 and is adapted to spray one or morecomponents of the motor stator 109, such as at least one end winding 113thereof.

While the present disclosure refers to oil, an oil pump, an oil filter,an oil spray bar, and an oil tube, it will be appreciated that anysuitable fluid for lubricating and cooling the motor 100 can be used,such as synthetic oil, and the like.

Referring now to FIG. 5 , a method 500 of warming oil for an electricmotor begins at a Start block 505. At a block 510, electrical power isprovided to a motor stator to warm a reservoir of oil. In variousembodiments, block 510 includes providing the electrical power from amotor drive, such as an inverter, where the electric power has a fixedmagnitude and is configured to inject current on the d-axis to ensurezero torque generation. In various embodiments, the current magnitude isselected such that the windings heat up in a short period of time, butwithout exceeding thermal limitations of the windings. In otherembodiments, a current is induced (fixed magnitude or otherwise) whileholding the motor rotor 115 stationary. In some of these embodiments,the motor rotor 115 is held stationary via one of a mechanical brake, avehicle braking system, a combination thereof, and the like.

In various embodiments, block 510 is performed in response to atemperature of the oil being below a predetermined temperature, such asbelow 0° Celsius, or while the temperature of the oil is within apredetermined range, such as from −30° Celsius to 0° Celsius. At a block520, oil is pumped from the reservoir of oil through a heat exchangerand to a sprayer. In various embodiments, the oil pump 102 is configuredto (such as via a controller) change the flow rate of the oil beginsupplied by the oil pump 102 once the oil reaches a predeterminedtemperature. In other embodiments, as will be detailed below in furtherdetail, the heat exchanger is at least partially bypassed until the oilreaches a predetermined temperature. At a block 530, oil may be sprayedfrom the sprayer onto exposed coil ends of the motor stator. At a block540, oil may be collected by the reservoir of oil. The method 500 endsat an End block 545.

By using the motor stator 109 to heat the oil, the viscosity of the oilcan be reduced, which reduces the impedance during distribution of theoil and allows the oil pump 102 to operate with a lower powerconsumption while still ensuring the proper lubrication and cooling ofthe components of the electrical motor system 100.

However, while the oil (or similar fluid) is at low temperatures, suchas between −30° Celsius and 30° Celsius, the high oil viscosity resultsin an increased system impedance and limits the amount of flow andpressure capacity that is available due to the finite power, flow, andpressure capability of the oil pump 102. As such, in variousembodiments, the electric motor system 100 is configured bypass at leastsome of the flow through the heat exchanger 104 based on a temperatureof the oil. This allows the oil pump 102 to operate at lowertemperatures and can reduce overloading of the oil pump 102 as well asincrease the operating life of the oil pump 102.

Referring to FIGS. 6 and 7 , in various embodiments, the electric motorsystem 100 includes a bypass valve 130 that is adapted to control anamount of oil that bypasses the heat exchanger 104 based on atemperature of the oil. In some embodiments, such as the embodimentillustrated in FIGS. 6 and 7 , the bypass valve 130 includes a valve 131that is passive. In various embodiments, the valve 131 includes astopper 133 and a core 132 causes the stopper 133 to move as the core132 heats up. In embodiments, the core 132 includes a material thatexpands upon heating, such as wax. In various embodiments, the stopper133 is pushed open via a spring 136, which pushes the stopper 133 intoan open position. In other embodiments, the valve 131 condition iscontrolled via a controller (such as controller 200 discussed below). Insome of these embodiments, the valve 131 is controlled via an electricor pneumatic actuator that is controlled based on the temperature of theoil.

In various embodiments, the bypass valve 130 includes a bypass inlet 134fluidly coupled to a heat exchanger inlet 117 and a bypass outlet 135fluidly coupled to a heat exchanger outlet 119. In other embodiments,the bypass inlet 134 is fluidly coupled to a supply line upstream of theheat exchanger inlet 117 and the bypass outlet 135 is fluidly coupled toa supply line downstream of the heat exchanger outlet 119.

In various embodiments, the electric motor system 100 is configured tooperate in a low-temperature mode while the oil temperature is below afirst predetermined temperature, a high-temperature mode while the oiltemperature is above a second predetermined temperature, and anintermediate-temperature mode while the oil temperature is between thefirst predetermined temperature and the second predeterminedtemperature. In the low-temperature mode, the bypass valve 130 is openand the oil bypasses the heat exchanger 104. In some embodiments, in thelow-temperature mode, the bypass valve 130 is fully open and the oilfully bypasses the heat exchanger 104. In the high-temperature mode, thebypass valve 130 is closed and the oil is directed through the heatexchanger 104. In some embodiments, the bypass valve is fully closed andthe oil is fully directed through the heat exchanger 104. In theintermediate-temperature mode, the bypass valve 130 is partially open.In embodiments, an amount of oil directed through the heat exchanger 104increases as the temperature of the oil increases until the bypass valve130 is fully closed at the second predetermined temperature. Inembodiments, an amount of oil bypassing the heat exchanger whileoperating in the intermediate-temperature mode is less than an amountbypassed while operating in the low-temperature mode and greater than anamount bypassed while operating in the high-temperature mode.

In various embodiments, the rating of the oil pump 102, such as forpower, flow, and pressure capabilities is based off of the systemimpedance with the oil at the first predetermined temperature and thebypass valve 130 is fully open. As such, in these embodiments, a lowerpower oil pump can be used to supply the oil throughout the electricmotor system 100, which can conserve energy and reduce any parasiticdrain the oil pump 102 causes in a vehicle.

In various embodiments, the oil is preheated using the motor stator 109,as discussed above, and the oil pump 102 increases a flowrate thereofonce the oil reaches a third predetermined temperature. In someembodiments, the third predetermined temperature is less than the firstpredetermined temperature. In other embodiments, the third predeterminedtemperature is equal to the first predetermined temperature.

In various embodiments, the first predetermined temperature is less than0° Celsius and the second predetermined temperature is greater than 0°Celsius. In other embodiments, the first predetermined temperature isbetween −35° Celsius and −25° Celsius, such as at −30° Celsius, and thesecond predetermined temperature is between 25° Celsius and 35° Celsius,such as at 30° Celsius. However, other temperatures for the firstpredetermined temperature and the second predetermined temperature arealso contemplated.

In various embodiments, the percentage that the bypass valve 130 is openfor controlling the amount of oil flowing through the heat exchanger 104in the intermediate-temperature mode is defined by a temperature-openingcurve. In various embodiments, the temperature-opening curve, includingthe first predetermined temperature and the second predeterminedtemperature, is based on at least one of a rating of the oil pump 102(power, flow, and pressure capabilities), viscosity of the oil at thevarious temperatures, and impedance of the oil delivery system (with orwithout flow through the heat exchanger 104).

Referring to FIG. 8 , the method 800 of bypassing a heat exchanger in anoil delivery system of an electric motor system includes operating in alow-temperature mode, bypassing the heat exchanger, while the oiltemperature is below a first predetermined temperature at step 802. Themethod also includes operating in a high-temperature mode, directing oiltraversing the oil delivery system through the heat exchanger while theoil temperature is above a second predetermined temperature at step 804.The method further includes operating in an intermediate-temperaturemode, partially bypassing the heat exchanger while the oil temperatureis between the first predetermined temperature and the secondpredetermined temperature, such that an amount of oil bypassing the heatexchanger while operating in the intermediate-temperature mode is lessthan an amount bypassed while operating in the low-temperature mode andgreater than an amount bypassed while operating in the high-temperaturemode at step 806.

Referring to FIG. 9 , in various embodiments an illustrative vehicle 700includes at least one drive member 702, at least one propulsion device704, at least one motor assembly 100, and at least one battery 706. Theat least one propulsion device 704 is coupled to the at least one drivemember 702. The at least one electric motor assembly 100 includes ahousing 118. The electric motor 114 is disposed in the housing 118 (FIG.2 ). The electric motor 114 includes the motor stator 109 having exposedend windings and a rotor 115 configured to rotate relative to the motorstator 109. The motor rotor 115 is coupled to the at least one drivemember 702. An oil sprayer 105 is configured spray fluid onto theexposed end windings 113 of the motor stator 109. Details of theelectric motor assembly 100, the electric motor 114, the motor rotor115, the motor stator 109, and the oil sprayer 105 have been describedabove and, for sake of brevity, details of their construction andoperation are not repeated (and need not be repeated for anunderstanding by a person of skill in the art).

In various embodiments, the electric motor assembly 100 further includesa motor drive 116 electrically coupled to the motor stator 109 and to abattery 706 of the vehicle 700. In various embodiments, the motor drive116 is an inverter. The motor drive 116 is configured to deliver powerfrom the battery 706 to the motor stator 109. In a drive mode, the motorstator 109 delivers power to induce torque in the motor rotor 115. Invarious embodiments, in the warming mode, the motor drive 116 isconfigured to deliver power without torque generation, such as bydelivering power with a fixed magnitude along the d-axis (d-axis currentinjection). In various embodiments, the electric motor assembly 100includes a controller 200 that is configured to control the motor drive116 and the power delivered therefrom.

It will be appreciated that the vehicle 700 can be any type of vehiclewhatsoever as desired without limitation. Given by way of non-limitingexample, in various embodiments the vehicle 700 may be an electricvehicle (that is, an all-electrically driven vehicle) or a hybridvehicle. For example, and given by way of non-limiting examples, invarious embodiments the vehicle 700 may include a motor vehicle drivenby wheels and/or tracks, such as, without limitation, an automobile, atruck, a sport utility vehicle (SUV), a van, an all-terrain vehicle(ATV), a motorcycle, an electric bicycle, a tractor, a lawn mower suchas without limitation a riding lawn mower, a snowmobile, and the like.Given by way of further non-limiting examples, in various embodimentsthe vehicle 700 may include a marine vessel such as, without limitation,a boat, a ship, a submarine, a submersible, an autonomous underwatervehicle (AUV), and the like. Given by way of further non-limitingexamples, in various embodiments the vehicle 700 may include an aircraftsuch as, without limitation, a fixed wing aircraft, a rotary wingaircraft, and a lighter-than-air (LTA) craft.

In various embodiments the electric motor (or motors) 114 are configuredto drive the vehicle 700. That is, in various embodiments the electricmotor (or motors) 114 may drive any drive member 702 that drives anypropulsion device 704, such as without limitation a wheel or wheels, atrack or tracks, a propellor or propellors, a propulsor or propulsors, arotor or rotors, or the like, associated with the vehicle 700.

For example, in some embodiments in a motor vehicle one electric motor114 may be configured to drive one drive member 702 such as an axle or achain ring that drives one wheel or track, in some other embodiments ina motor vehicle one electric motor 114 may be configured to drive anaxle that rotates two wheels or two tracks, and in some otherembodiments in a motor vehicle one electric motor 114 may be configuredto drive an axle that rotates one wheel or one track and another motorconfigured to drive another axle that rotates another wheel or anothertrack.

Similarly, in some embodiments in a marine vessel one electric motor 102may be configured to drive one propeller or propulsor, in some otherembodiments in a marine vessel one electric motor 114 may be configuredto drive a shaft that rotates two propellers or two propulsors, and insome other embodiments in a marine vessel one electric motor 114 may beconfigured to drive a shaft that rotates one propeller or propulsor andanother electric motor 114 may be configured to drive another shaft thatrotates another propeller or propulsor.

Likewise, in some embodiments in an aircraft one electric motor 114 maybe configured to drive one propeller or rotor, in some other embodimentsin an aircraft one electric motor 114 may be configured to drive a shaftthat rotates two propellers or two rotors, and in some other embodimentsin an aircraft one electric motor 114 may be configured to drive a shaftthat rotates one propeller or rotor and another electric motor 114 maybe configured to drive another shaft that rotates another propeller orrotor.

Referring to FIG. 10 , the controller 200 may be a digital computerthat, in terms of hardware architecture, generally includes a processor202, input/output (I/O) interfaces 204, a network interface 206, a datastore 208, and memory 210. It should be appreciated by those of ordinaryskill in the art that FIG. 8 depicts the controller 200 in anoversimplified manner, and a practical embodiment may include additionalcomponents and suitably configured processing logic to support known orconventional operating features that are not described in detail herein.The components (202, 204, 206, 208, and 210) are communicatively coupledvia a local interface 212. The local interface 212 may be, for example,but not limited to, one or more buses or other wired or wirelessconnections, as is known in the art. The local interface 212 may haveadditional elements, which are omitted for simplicity, such ascontrollers, buffers (caches), drivers, repeaters, and receivers, amongmany others, to enable communications. Further, the local interface 212may include address, control, and/or data connections to enableappropriate communications among the aforementioned components.

The processor 202 is a hardware device for executing softwareinstructions. The processor 202 may be any custom made or commerciallyavailable processor, a central processing unit (CPU), an auxiliaryprocessor among several processors associated with the controller 200, asemiconductor-based microprocessor (in the form of a microchip orchipset), or generally any device for executing software instructions.When the controller 200 is in operation, the processor 202 is configuredto execute software stored within the memory 210, to communicate data toand from the memory 210, and to generally control operations of thecontroller 200 pursuant to the software instructions. The I/O interfaces214 may be used to receive input from and/or for providing system outputto one or more devices or components. I/O interfaces 34 may include, forexample, a serial port, a parallel port, a small computer systeminterface (SCSI), a serial ATA (SATA), a fiber channel, Infiniband,iSCSI, a PCI Express interface (PCI-x), an infrared (IR) interface, aradio frequency (RF) interface, and/or a universal serial bus (USB)interface.

The network interface 36 may be used to enable the controller 200 tocommunicate on a network, such as a network associated with the vehicle,to communicate with other devices and components of the vehicle, and thelike. A data store 208 may be used to store data. The data store 208 mayinclude any of volatile memory elements (e.g., random access memory(RAM, such as DRAM, SRAM, SDRAM, and the like)), nonvolatile memoryelements (e.g., ROM, hard drive, tape, CDROM, and the like), andcombinations thereof. Moreover, the data store 208 may incorporateelectronic, magnetic, optical, and/or other types of storage media. Inone example, the data store 208 may be located internal to thecontroller 200, such as, for example, an internal hard drive connectedto the local interface 212 in the controller 200. Additionally, inanother embodiment, the data store 208 may be located external to thecontroller 200.

The memory 210 may include any of volatile memory elements (e.g., randomaccess memory (RAM, such as DRAM, SRAM, SDRAM, etc.)), nonvolatilememory elements (e.g., ROM, hard drive, tape, CDROM, etc.), andcombinations thereof. Moreover, the memory 210 may incorporateelectronic, magnetic, optical, and/or other types of storage media. Notethat the memory 210 may have a distributed architecture, where variouscomponents are situated remotely from one another, but can be accessedby the processor 202. The software in memory 210 may include one or moresoftware programs, each of which includes an ordered listing ofexecutable instructions for implementing logical functions. The softwarein the memory 210 includes a suitable operating system (O/S) 214 and oneor more programs 216. The operating system 214 essentially controls theexecution of other computer programs, such as the one or more programs216, and provides scheduling, input-output control, file and datamanagement, memory management, and communication control and relatedservices. The one or more programs 216 may be configured to implementthe various processes, algorithms, methods, techniques, etc. describedherein.

It will be appreciated that some embodiments described herein mayinclude or utilize one or more generic or specialized processors (“oneor more processors”) such as microprocessors; Central Processing Units(CPUs); Digital Signal Processors (DSPs): customized processors such asNetwork Processors (NPs) or Network Processing Units (NPUs), GraphicsProcessing Units (GPUs), or the like; Field-Programmable Gate Arrays(FPGAs); and the like along with unique stored program instructions(including both software and firmware) for control thereof to implement,in conjunction with certain non-processor circuits, some, most, or allof the functions of the methods and/or systems described herein.Alternatively, some or all functions may be implemented by a statemachine that has no stored program instructions, or in one or moreApplication-Specific Integrated Circuits (ASICs), in which each functionor some combinations of certain of the functions are implemented ascustom logic or circuitry. Of course, a combination of theaforementioned approaches may be used. For some of the embodimentsdescribed herein, a corresponding device in hardware and optionally withsoftware, firmware, and a combination thereof can be referred to as“circuitry configured to,” “logic configured to,” etc. perform a set ofoperations, steps, methods, processes, algorithms, functions,techniques, etc. on digital and/or analog signals as described hereinfor the various embodiments.

Moreover, some embodiments may include a non-transitorycomputer-readable medium having instructions stored thereon forprogramming a computer, server, appliance, device, processor, circuit,etc. to perform functions as described and claimed herein. Examples ofsuch non-transitory computer-readable medium include, but are notlimited to, a hard disk, an optical storage device, a magnetic storagedevice, a Read-Only Memory (ROM), a Programmable ROM (PROM), an ErasablePROM (EPROM), an Electrically EPROM (EEPROM), Flash memory, and thelike. When stored in the non-transitory computer-readable medium,software can include instructions executable by a processor or device(e.g., any type of programmable circuitry or logic) that, in response tosuch execution, cause a processor or the device to perform a set ofoperations, steps, methods, processes, algorithms, functions,techniques, etc. as described herein for the various embodiments.

In some instances, one or more components may be referred to herein as“configured to,” “configured by,” “configurable to,” “operable/operativeto,” “adapted/adaptable,” “able to,” “conformable/conformed to,” etc.Those skilled in the art will recognize that such terms (for example“configured to”) generally encompass active-state components and/orinactive-state components and/or standby-state components, unlesscontext requires otherwise.

While particular aspects of the present subject matter described hereinhave been shown and described, it will be apparent to those skilled inthe art that, based upon the teachings herein, changes and modificationsmay be made without departing from the subject matter described hereinand its broader aspects and, therefore, the appended claims are toencompass within their scope all such changes and modifications as arewithin the true spirit and scope of the subject matter described herein.It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (for example, bodiesof the appended claims) are generally intended as “open” terms (forexample, the term “including” should be interpreted as “including butnot limited to,” the term “having” should be interpreted as “having atleast,” the term “includes” should be interpreted as “includes but isnot limited to,” etc.). It will be further understood by those withinthe art that if a specific number of an introduced claim recitation isintended, such an intent will be explicitly recited in the claim, and inthe absence of such recitation no such intent is present. For example,as an aid to understanding, the following appended claims may containusage of the introductory phrases “at least one” and “one or more” tointroduce claim recitations. However, the use of such phrases should notbe construed to imply that the introduction of a claim recitation by theindefinite articles “a” or “an” limits any particular claim containingsuch introduced claim recitation to claims containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (for example, “a” and/or “an” should typically be interpreted tomean “at least one” or “one or more”); the same holds true for the useof definite articles used to introduce claim recitations. In addition,even if a specific number of an introduced claim recitation isexplicitly recited, those skilled in the art will recognize that suchrecitation should typically be interpreted to mean at least the recitednumber (for example, the bare recitation of “two recitations,” withoutother modifiers, typically means at least two recitations, or two ormore recitations). Furthermore, in those instances where a conventionanalogous to “at least one of A, B, and C, etc.” is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (for example, “a system having at leastone of A, B, and C” would include but not be limited to systems thathave A alone, B alone, C alone, A and B together, A and C together, Band C together, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that typically a disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms unless context dictates otherwise. For example, the phrase “Aor B” will be typically understood to include the possibilities of “A”or “B” or “A and B.”

The foregoing detailed description has set forth various embodiments ofthe devices and/or processes via the use of block diagrams, flowcharts,and/or examples. Insofar as such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, it will beunderstood by those within the art that each function and/or operationwithin such block diagrams, flowcharts, or examples can be implemented,individually and/or collectively, by a wide range of hardware.

With respect to the appended claims, those skilled in the art willappreciate that recited operations therein may generally be performed inany order. Also, although various operational flows are presented in asequence(s), it should be understood that the various operations may beperformed in other orders than those which are illustrated or may beperformed concurrently. Examples of such alternate orderings may includeoverlapping, interleaved, interrupted, reordered, incremental,preparatory, supplemental, simultaneous, reverse, or other variantorderings, unless context dictates otherwise. Furthermore, terms like“responsive to,” “related to,” or other past-tense adjectives aregenerally not intended to exclude such variants, unless context dictatesotherwise.

While the disclosed subject matter has been described in terms ofillustrative embodiments, it will be understood by those skilled in theart that various modifications can be made thereto without departingfrom the scope of the claimed subject matter as set forth in the claims.

What is claimed is:
 1. An electrical motor system comprising: an oilreservoir configured to hold oil therein; a motor stator positioned suchthat at least a portion thereof is positioned within the oil reservoirwhere the at least the portion of the motor stator is in thermalcommunication with the oil while the oil reservoir includes the oiltherein, the motor stator being configured to warm the oil while in anoil warming mode; and an oil pump fluidly coupled to the oil reservoirand configured to draw oil out of the oil reservoir.
 2. The electricalmotor system of claim 1, wherein the oil reservoir includes an oil sumpand the at least the portion of the motor stator is positioned withinthe oil sump and at least partially submerged in the oil.
 3. Theelectrical motor system of claim 1, further comprising: a motor rotor;and a

tor drive electrically coupled to the motor stator, the motor driveconfigured to induce a current in the motor stator in the oil warmingmode while the motor rotor remains static during the oil warming mode.4. The electrical motor system of claim 3, wherein the motor drive is aninverter and the inverter is configured to induce a current injectionwith a fixed magnitude along a d-axis such that zero torque is generatedin the motor rotor.
 5. The electrical motor system of claim 1, whereinthe oil warming mode is initiated in response to the oil being within apredetermined temperature range.
 6. The electrical motor system of claim5, wherein the predetermined temperature range is from minus thirtydegrees Celsius to zero degrees Celsius.
 7. The electrical motor systemof claim 1, wherein the oil pump is configured to increase a flowrate ofthe oil once a temperature of the oil reaches a predeterminedtemperature while the motor stator is operating in the oil warming mode.8. An electric motor comprising: a motor stator; a motor rotorconfigured to rotate relative to the motor stator; an oil reservoirconfigured to hold oil therein such that a portion of the motor statoris in thermal communication with the oil while the oil reservoir includethe oil therein, the motor stator being electrically couplable toreceive electrical power in an oil warming mode, the motor stator beingconfigured to increase a temperature of the oil while in the oil warmingmode; and an oil pump fluidly coupled to the oil reservoir andconfigured to draw oil out of the oil reservoir.
 9. The electric motorof claim 8, wherein the motor stator is configured to generate zerotorque in the motor rotor during the oil warming mode.
 10. The electricmotor of claim 8, further comprising a motor drive electrically coupledto the motor stator, the motor drive configured to induce a current inthe motor stator in the oil warming mode while the motor rotor remainsstatic during the oil warming mode.
 11. The electric motor of claim 10,wherein the motor drive is an inverter and the inverter is configured toinduce a current injection with a fixed magnitude along a d-axis suchthat zero torque is generated in the motor rotor.
 12. The electric motorof claim 8, wherein the oil warming mode is initiated in response to theoil being within a predetermined temperature range.
 13. The electricmotor of claim 8, wherein the predetermined temperature range is fromminus thirty degrees Celsius to zero degrees Celsius.
 14. The electricmotor of claim 8, wherein the oil pump is configured to increase aflowrate of the oil once a temperature of the oil reaches apredetermined temperature while the motor stator is operating in the oilwarming mode.
 15. A vehicle comprising: a vehicle body; an electricalmotor system including an oil reservoir configured to hold oil therein,a motor stator positioned such that at least a portion thereof ispositioned within the oil reservoir where the at least the portion ofthe motor stator is in thermal communication with the oil while the oilreservoir includes the oil therein, the motor stator being configured towarm the oil while in an oil warming mode, and an oil pump coupled tothe oil reservoir and configured to draw oil out of the oil reservoir;and at least one wheel coupled to the vehicle body and configured to bedriven by at least one motor having a motor stator and a motor rotorcoupled to a drivetrain for the at least one wheel, the motor rotorbeing configured to rotate relative to the motor stator.
 16. The vehicleof claim 15, wherein the electrical motor system further comprises: amotor rotor; and a motor drive electrically coupled to the motor stator,the motor drive configured to induce a current in the motor stator inthe oil warming mode while the motor rotor remains static during the oilwarming mode.
 17. The vehicle of claim 16, wherein the motor drive is aninverter and the inverter is configured to induce a current injectionwith a fixed magnitude along a d-axis such that zero torque is generatedin the motor rotor.
 18. The vehicle of claim 15, wherein the oil warmingmode is initiated in response to the oil being within a predeterminedtemperature range.
 19. The vehicle of claim 18, wherein thepredetermined temperature range is from minus thirty degrees Celsius tozero degrees Celsius.
 20. The vehicle of claim 15, wherein the oil pumpis configured to increase a flowrate of the oil once a temperature ofthe oil reaches a predetermined temperature while the motor stator isoperating in the oil warming mode.